Comparison of the acute toxicity for gamma-cyhalothrin and lambda-cyhalothrin to zebra fish and shrimp

Nanotechnology in agriculture: a review of genotoxic studies of nanopesticides in animal cells

Agriculture has been and still is one of the most influential primary operations in economic history worldwide. Its social, cultural, and political impact allows the progression and survival of humanity. Sustaining the supply of primary resources is crucial for the future. Therefore, the development of new technologies applied to agrochemicals is growing to obtain better food quality faster. Recently, nanotechnology has gained strength in this field in the last decade, mainly because of the presumed benefits that will carry with it compared with the current commercial presentations, like the decrease of risk in non-target organisms. The harm of pesticides is commonly associated with unwanted effects on human health, some with long-term genotoxic effects. Therefore, it would be relevant to set the existence of a risk or a benefit of the nanopesticides from a genotoxic point of view, comparing against those without this technology. Although some studies are concerned with its genotoxicity in live aquatic organisms, few focus on human in vitro models. Several studies conclude that some of them can induce oxidative stress, leading to DNA damage or cell death. However, there is still much to investigate to establish an accurate and complete assessment. In this review, we aim to give an overview of the genotoxic effect caused by nanopesticides in animal cells and a guide to the evolution of this topic, offering a base and critical review to facilitate future research.

Comparison of the genotoxicity of two commercial pesticides by their micro and nano size capsules

The use of nanotechnology in the agrochemical industry has become increasingly popular over the past decade, raising the question of whether these products may represent a risk or benefit compared to their conventional presentations. In this study, we aimed to evaluate the different genotoxic effects of the Complete encapsulated presentation (CEP), the micro encapsulated fraction (MEF), and the nano encapsulated fraction (NEF) of two pesticides (Karate® and Ampligo®) in lymphocytes from human peripheral blood. To test the different fractions, the pesticides were separated by centrifugations by the average size of the capsule, then were characterized by the general composition of the capsule by RAMAN and FTIR spectroscopy and the active ingredient of both pesticides by gas chromatography-mass spectrometry. Each fraction was tested separately and analyzed by comet assay through the tail moment and the percentage of DNA in the tail and the cytokinesis-block micronucleus through their frequency of micronucleus, nucleoplasmic bridges, and nuclear buds. The nuclear division index and the Nuclear Division Cytotoxicity Index were also measured. For both pesticides, the CEP increased the genetic damage observed in the tail moment and percentage of DNA in the tail at all concentrations for both pesticides. However, in the micronucleus test, NEF induced more micronuclei than MEF and CEP in all treatments reducing cell proliferation as the concentration decreased for both pesticides. These results suggested that NEF had more genotoxic effects in both pesticides, increasing the damage to the cells.

Behavior of two classes of organic contaminants in the presence of graphene oxide: Ecotoxicity, physicochemical characterization and theoretical calculations

Graphene oxide (GO) production has increased considerably and therefore its presence in the environment is inevitable. When in aquatic environment GO can interact with co-existing compounds, modifying their toxicities for several organisms. However, the toxic effects of co-exposure of GO and organic compounds are rarely reported in the literature. Herein, we studied the behavior of four organic aquatic contaminants found in surface water such as 2-phenylbenzotriazoles (non-Cl PBTA-9 and PBTA-9) and phenoxyphenyl pesticides, pyriproxyfen (PYR) and lambdacyhalothrin (LCT), in the presence of GO. GO reduced 90% and 83% of the toxicity of non-Cl PBTA-9 and PBTA for Daphnia. When PBTAs were adsorbed onto GO surface their interactions caused GO agglomeration (up to 20 mm) and consequent precipitation, making PBTAs less bioavailable. PYR and LCT's toxicities increased up to 83% for PYR and 47% for LCT in the presence of GO, because their adsorption on GO lead to the stabilization of the suspensions (up to 0.5 μm). Those particles were then easily ingested and retained in the digestive tract of the daphnids, triggering the Trojan horse effect. Based on theoretical calculations we observed that PBTA compounds are planar, electron-poorer and more reactive than the studied pesticides, suggesting a better stability of the GO/PBTA complexes. PYR and LCT are nonplanar, electron-richer and less reactive towards GO than PBTAs, forming less stable GO complexes that could facilitate the desorption of pesticides, increasing toxic effects. Our results suggest that the properties of the organic toxicants can influence the stability of graphene oxide suspensions, playing a fundamental role in the modulation of their toxicity. Further research is needed for a deep understanding of the behavior of nanomaterials in the presence of contaminants and their effect in the toxicity of aquatic organisms.

Fabrication and evaluation of Lambda-Cyhalothrin nanosuspoemulsion with pH- and temperature-responsive based on polyethylene wax as carrier

Using polyethylene wax (PW) as the coating matrix, the lambda-cyhalothrin-PW nanosuspoemulsion (LC-PW) with a particle size of 80-150nm was prepared through high-speed stirring, hot melt emulsification and ultrasonic dispersion. The formulation and composition of the LC-PW were optimized, the morphology of the LC-PW was analyzed by dynamic light scattering (DLS) and TEM, and the structure of the LC-PW was characterized by UV and IR. The anti-photolysis test showed that LC-PW had a good anti-photolysis performance. Furthermore, LC-PW could sustainably release Lambda-cyhalothrin, which was pH- and temperature dependent. The insecticidal activity analysis in the greenhouse indicated that the toxic strength between LC-PW and LC-SC (lambda-cyhalothrin-suspension concentrate) to Mythimna separata was similar within the same concentration ranges tested, but the insecticidal duration of LC-PW was significantly longer than LC-SC. Thus, the new type of LC-PW with the properties of anti-photolysis and controlled release is suitable for application in the field as a better insecticide.

Behavior of acetamiprid, azoxystrobin, pyraclostrobin, and lambda-cyhalothrin in/on pomegranate tissues

Pomegranate crop is affected by several insect pests and requires usage of a large number of pesticides, but the information on their behavior in pomegranate tissues is limited. A study was conducted to assess the behavior of acetamiprid, azoxystrobin, pyraclostrobin, and lambda-cyhalothrin in pomegranate fruits and leaves. The QuEChERS analytical method and LC-MS/MS and GC-MS were used for quantification of the analytes. The LOD (limit of detection) of acetamiprid, azoxystrobin, and pyraclostrobin was 0.0015 mg kg^-1 and lambda-cyhalothrin was 0.003 mg kg^-1. The respective LOQ (limit of quantification) was 0.005 and 0.01 mg kg^-1. The dissipation of the analytes best fitted into first-order rate kinetics and the half-lives of the chemicals in pomegranate fruits were 9.2-13 days and in the leaves were 13.5-17 days. In the pomegranate aril, the residue levels of acetamiprid, lambda-cyhalothrin, and pyraclostrobin were always < LOQ of these chemicals. Azoxystrobin was detected in pomegranate aril, and its residue was highest at 0.04 mg kg^-1 on the 10th day and reached < LOQ by the 25th day. The pre-harvest interval (PHI) required for acetamiprid, azoxystrobin, pyraclostrobin, and lambda-cyhalothrin at standard-dose treatment was 50, 58, 44, and 40 days, respectively. From double-dose treatment, the PHIs were 70, 75, 58, and 54 days, respectively. The pesticides used in this study were more persistent in the pomegranate leaves compared to the fruits. The outcome of this study can be incorporated into production of pomegranate fruits safe for consumption and to meet the domestic and export quality control requirements.

Eco-friendly Water-Based λ-Cyhalothrin Polydopamine Microcapsule Suspension with High Adhesion on Leaf for Reducing Pesticides Loss

Recently, innovations of nano/microcarrier formulations have been focused on improving application efficiencies and retention time. In this study, a water-based 2.5% λ-cyhalothrin (LC) microcapsule suspension (CS) was developed by orthogonal test with biodegradable and adhesive polydopamine (PDA) microcapsules (MCs) as carriers. The obtained LC-PDA CS had good suspension properties, flow behavior, storage stability, and rheological properties. LC-PDA CS had higher retention, wettability, and decreased rainwater washing out on the leaves than commercial CS. LC-PDA CS displayed higher insecticidal activity against Lipaphis erysimi compared to commercial CS. LC-PDA CS reduced the toxicity of LC to the aquatic organism Danio rerio compared to LC. The above results demonstrated that LC-PDA CS would be eco-friendly water-based pesticides carrier system for prolonging the retention time on target leaf and reducing toxicity to aquatic organisms.

Dual immunological and oxidative responses in Oreochromis niloticus fish exposed to lambda cyhalothrin and concurrently fed with Thyme powder (Thymus vulgaris L.): Stress and immune encoding gene expression

The present study was performed to explore the immunotoxicological effects of the lambda cyhalothrin (LCH) insecticide and evaluate the efficiency of Thyme powder (TP) as a fish supplement in attenuation of LCH impact on Oreochromis niloticus (O. niloticus) fish. Fish was sampled following 30-days exposure to LCH (¹/₆ LC50: 0.48 μg/L) and TP (2%) supplementation, individually or in combination. The growth performance, immune status, biochemical indices, and mRNA expression pattern changes of stress and immune-encoding genes in the liver and spleen tissues, respectively, through real-time polymerase chain reaction (RT-PCR) analysis, were evaluated. The findings showed that LCH exposure caused a significant lowering in most of the estimated variables including growth performance, hematological and immunological indices. Moreover, LCH disrupted the oxidant/antioxidant status and dysregulated the expression of stress and immune-related genes, downregulating the mRNA transcript level of Immunoglobulin M heavy chain (IgM), Interferon (IFN-γ), CXC-chemokine, and Toll-like receptors (TLR-7) in the spleen. However, mRNA expression of Myxovirus resistance (Mx) gene remained unaffected. In liver tissue, the heat shock protein (HSP-70) expression was upregulated, while that of cytochrome P450 1A (CYP 1A) was downregulated. TP (2%) supplementation elicited a significant modulation in aforementioned indices; however, their levels did not attain that of the control values. Our findings concluded that LCH affects the O. niloticus immune response through the negative transcriptional influence on genes linked to immunity and induction of oxidative injury of the immune organs. Besides, dietary TP (2%) could be a proper candidate to modulate the compromised immunity in response to LCH exposure in O. niloticus aquaculture.

Comparative acute toxicity of two phytosanitary molecules, lambda-cyhalothrin and acetamiprid, on Nile Tilapia (Oreochromis Niloticus) juveniles

This study aimed to compare the toxicity for fish of two active ingredients (lambda-cyhalothrin-20 g L^-1, a pyrethroid, and acetamiprid-15 g L^-1, a neonicotinoid) which are components of a commercial insecticide (Acer 35 EC) used in cotton crop in many West African countries. The juveniles of Oreochromis niloticus (4.01 ± 0.34 g, mean body weight) were exposed for 96 h to increasing concentrations of active ingredients (lambda-cyhalothrin and acetamiprid) or a mixture similar to Acer 35 EC (composed by 20 g of chemical compound lambda-cyhalothrin and 15 g of acetamiprid dissolved in 1 L of acetone). The experiments were carried out under controlled conditions in aquaria according to OECD Guidelines. During the experiments, the behavioral responses (loss of balance, color change, hyperactivity, etc.) that usually precede death were observed in exposed fish. Mortalities were recorded in each aquarium and the LC₅₀-96h of each chemical was determined. The LC₅₀-96h obtained were respectively 0.1268, 0.0029, 182.9 and 0.5685 ppm for Acer 35 EC, lambda-cyhalothrin, acetamiprid and mixture. All insecticides used in this study had profound impact on Nile tilapia behavior which may confirm the neurotoxicity of each single active compound as well as of their mixture.

Stable carbon isotope fractionation during the biodegradation of lambda-cyhalothrin

In this study, the microbial degradation of lambda-cyhalothrin in soil was investigated using compound-specific stable isotope analysis. The results revealed that lambda-cyhalothrin was biodegraded in soil under laboratory conditions. The half-lives of lambda-cyhalothrin were determined to be 49 and 161 days in non-sterile and sterile soils spiked with 2mg/kg lambda-cyhalothrin and 84 and 154 days in non-sterile and sterile soils spiked with 10mg/kg lambda-cyhalothrin, respectively. The biodegradation of lambda-cyhalothrin resulted in carbon isotope fractionation, which shifted from -29.0‰ to -26.5‰ in soil spiked with 2mg/kg lambda-cyhalothrin, and to -27.5‰ with 10mg/kg lambda-cyhalothrin. A relationship was established between the stable carbon isotope fraction and the residual concentrations of lambda-cyhalothrin by the Rayleigh equation in which the carbon isotope enrichment factor ε of the microbial degradation of lambda-cyhalothrin in the soil was calculated as -2.53‰. This study provides an approach to quantitatively evaluate the biodegradation of lambda-cyhalothrin in soil in field studies.

Application of the response surface and desirability design to the Lambda-cyhalothrin degradation using photo-Fenton reaction

Lambda-cyhalothrin is a potent pyrethroid insecticide used widely in pest management. Detectable levels of the pyrethroid in agricultural watersheds are potentially toxic to aquatic organisms. There is little information in the scientific literature about degradation in aqueous media of the Lambda-cyhalothrin by Advanced Oxidative Process. A mathematical approach for the degradation of this compound has not yet been fully explored… The Central composite design (CCD) and response surface method (RSM) were applied to evaluate and optimize the interactive effects of two operating variables. The initial dosages of H2O2 and Fe(2+) on photo-Fenton degradation of an aqueous solution of Lambda-cyhalothrin in a recirculation flow-through UV photoreactor were used. The remaining concentration of Lambda-cyhalothrin (y1) and the percentage removal of total organic carbon (y2) were the monitored factors since they are dependent parameters of y1 and y2. According to analysis of variances (ANOVA) results, two proposed models can be used to navigate the design space with regression coefficient R(2) - 0.834 and 0.843 for y1 and y2, respectively. A multi-response optimization procedure, based on the global desirability of the factors, was performed to establish the best concentrations of hydrogen peroxide and ferrous sulfate that would allow the most efficient degradation of Lambda-cyhalothrin concomitant with a maximal removal of total organic carbon. The global desirability surface revealed that 0.295 mmol L(-1) of ferrous sulfate and 3.85 mmol L(-1) of hydrogen peroxide were close to the optimum conditions to satisfy both factors simultaneously using minimal amounts of reagents. These photo-Fenton conditions promoted 100% of Lambda-cyhalothrin degradation and 79.83% TOC removal (mineralization) in 120 min of reaction time.

Combined effect of invertebrate predation and sublethal pesticide exposure on the behavior and survival of Asellus aquaticus (Crustacea; Isopoda)

Invertebrate communities of lentic habitats comprise, amongst others, the crustacean Asellus aquaticus (Isopoda) and the turbellarian Dendrocoelum lacteum (Tricladida). Because D. lacteum preferentially preys on A. aquaticus, contaminants introduced into the aquatic environment may affect this predator-prey interaction, finally influencing the performance of the predator. However, no studies investigating implications of organic pollutants on this food web subsystem currently exist. Hence, the present study assessed short-term implications of pesticides with different modes of action, namely, the triazole fungicide tebuconazole and the pyrethroid insecticide lambda-cyhalothrin, during a 72 h trial. The experiments for tebuconazole showed a statistically significant decrease in predatory success of D. lacteum. Lambda-cyhalothrin, in contrast, increased predation success by 40%, which is, however, not statistically significant. Both the decrease and the increase in predation seemed to be primarily driven by an altered activity of the prey A. aquaticus. This may be hypothesized because any shift in the prey's activity influenced its probability to stick to mucus, a viscous substance released by D. lacteum, or to encounter the predator directly.

Cholinergic dysfunctions and enhanced oxidative stress in the neurobehavioral toxicity of lambda-cyhalothrin in developing rats

This study is focused on understanding the mechanism of neurobehavioral toxicity of lambda-cyhalothrin, a new generation type II synthetic pyrethroid in developing rats following their exposure from post-lactational day (PLD)22 to PLD49 and investigate whether neurobehavioral alterations are transient or persistent. Post-lactational exposure to lambda-cyhalothrin (1.0 or 3.0 mg/kg body weight, p.o.) affected grip strength and learning activity in rats on PLD50 and the persistent impairment of grip strength and learning was observed at 15 days after withdrawal of exposure on PLD65. A decrease in the binding of muscarinic-cholinergic receptors in frontocortical, hippocampal, and cerebellar membranes associated with decreased expression of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in hippocampus was observed following exposure to lambda-cyhalothrin on PLD50 and PLD65. Exposure to lambda-cyhalothrin was also found to increase the expression of growth-associated protein-43 in hippocampus of rats on PLD50 and PLD65 as compared to controls. A significant increase in lipid peroxidation and protein carbonyl levels and decreased levels of reduced glutathione and activity of superoxide dismutase, catalase, and glutathione peroxidase in brain regions of lambda-cyhalothrin exposed rats were distinctly observed indicating increased oxidative stress. Inhibition of ChAT and AChE activity may cause down-regulation of muscarinic-cholinergic receptors consequently impairing learning activity in developing rats exposed to lambda-cyhalothrin. The data further indicate that long-term exposure to lambda-cyhalothrin at low doses may be detrimental and changes in selected behavioral and neurochemical end points may persist if exposure to lambda-cyhalothrin continues.

Toxic effects of deltamethrin and λ-cyhalothrin on Xenopus laevis tadpoles

This study evaluates the toxic effects of deltamethrin and λ-cyhalothrin on Xenopus laevis tadpoles after 168 h of exposure. The LC(50) of deltamethrin and λ-cyhalothrin at 168 h was calculated as the μg of active ingredient per liter (μg AI/L). According to these values, the LC(50) was 6.26 and 3.94 μg AI/L for deltamethrin and λ-cyhalothrin, respectively. Several enzymes were studied for early signs of intoxication following exposure to the pesticides for 24 h. Glutathione-S-transferase,carboxylesterase, and lactate dehydrogenase were inhibited by λ-cyhalothrin, and both pesticides inhibited acid phosphatase and aspartate aminotransferase. In contrast, acetylcholinesterase was activated by deltamethrin. The results suggest that X. laevis is sensitive to the pyrethroids that were tested, and the enzyme responses suggest that they are potential biomarkers for evaluating the toxic effect of pyrethroids on amphibians in environmental conditions.

Cytotoxicity of lambda-cyhalothrin on the macrophage cell line RAW 264.7

The wide use and wide-spectrum toxicity of synthetic pyrethroids (SPs) insecticides make them an emerging ecotoxicological concern. Some previous studies showed that SPs possessed cytotoxicity in some immune cells such as human lymphocytes and rat bone marrow. However, the cytotoxicity of SPs to macrophages, which are crucial to innate immunity, has not been explored. In the present report, we investigated a new pyrethroid insecticide, lambda-cyhalothrin (LCT), which may increase the generation of reactive oxygen species (ROS) and DNA damage levels and cause cytotoxicity in RAW 264.7 cells in dose- and time-dependent manners. The results for the first time implicated increased endogenous ROS and DNA damage as co-mediators of LCT-induced cytotoxicity in macrophages. Our results also suggested that macrophages were involved in synthetic pyrethroid-induced adverse immune effects. Considering the ubiquitous environmental presence of SPs, this study provided new information relative to the potential long-term physiological and immunological effects associated with chronic exposure to SPs. Hence, the potential immunotoxicity of SPs should be considered in assessing the safety of these compounds in sensitive environmental compartments.

Effects of the pyrethroid insecticide gamma-cyhalothrin on aquatic invertebrates in laboratory and outdoor microcosm tests

The sensitivity of a range of freshwater lentic invertebrates to gamma-cyhalothrin (GCH), a single enantiomer of the synthetic pyrethroid lambda-cyhalothrin, was assessed in single species laboratory tests and an outdoor multi-species ecosystem test. The most sensitive species in the laboratory single species tests with GCH was Chaoborus obscuripes (96 h EC(50): 3.8 ng/l). The species sensitivity distribution curve, based on the laboratory 96 h EC(50) acute toxicity data for eight species, gave a median HC(5) value for GCH of 2.12 ng/l. The NOEC(community) derived from the multi-species ecosystem test was 5 ng/l, and the insects Chaoborus sp. and Caenis sp. were identified as the most sensitive species. The results indicate that the median HC(5), based on eight species selected to include those known to be sensitive to pyrethroids, provided a good estimation of the NOEC(community) for GCH. Furthermore, the results for GCH indicated that the endpoints typically used in higher-tier risk assessments for pesticides in Europe (HC(5) and NOEC(community)) were consistent with expectations when compared to the equivalent endpoints for the racemate LCH.

Acute toxicity of pesticides to the tropical freshwater shrimp Caridina laevis

To determine the potential risk of pesticides frequently used in Indonesia, a new toxicity test was developed using the indigenous freshwater shrimp Caridina laevis, which is representative of tropical ecosystems. The test species could easily be maintained in the laboratory. Acute toxicity tests with different insecticides, fungicides, and herbicides assessing adult survival after 24 and 96 h of static exposure showed low control mortality (<10%) and good reproducibility for diazinon. Juvenile C. laevis appeared approximately two to three times more sensitive to diazinon than adult ones. Compared to other species of freshwater crustacean commonly used in standard aquatic toxicity tests, C. laevis showed similar sensitivity for diazinon and lambda cyhalothrin, much greater sensitivity for endosulfan and paraquat and much lower sensitivity for carbofuran. It may be concluded that the acute toxicity test using C. laevis may be a suitable alternative for determining the potential risk of chemicals under tropical conditions.

Environmental chemistry, ecotoxicity, and fate of lambda-cyhalothrin

Lambda-cyhalothrin is a pyrethroid insecticide used for controlling pest insects in agriculture, public health, and in construction and households. Lambda-cyhalothrin is characterized by low vapor pressure and a low Henry's law constant but by a high octanol-water partition coefficient (K(ow)) and high water-solid-organic carbon partition coefficient (K(oc)) values. Lambda-cyhalothrin is quite stable in water at pH < 8, whereas it hydrolyzes to form HCN and aldehyde under alkaline conditions. Although lambda-cyhalothrin is relatively photostable under natural irradiation, with a half-life > 3 wk, its photolysis process is fast under UV irradiation, with a half-life < 10 min. The fate of lambda-cyhalothrin in aquatic ecosystems depends on the nature of system components such as suspended solids (mineral and organic particulates) and aquatic organisms (algae, macrophytes, or aquatic animals). Lambda-cyhalothrin residues dissolved in water decrease rapidly if suspended solids and/or aquatic organisms are present because lambda-cyhalothrin molecules are strongly adsorbed by particulates and plants. Adsorbed lambda-cyhalothrin molecules show decreased degradation rates because they are less accessible to breakdown than free molecules in the water column. On the other hand, lambda-cyhalothrin adsorbed to suspended solids or bottom sediments may provide a mechanism to mitigate its acute toxicity to aquatic organisms by reducing their short-term bioavailability in the water column. The widespread use of lambda-cyhalothrin has resulted in residues in sediment, which have been found to be toxic to aquatic organisms including fish and amphipods. Mitigation measures have been used to reduce the adverse impact of lambda-cyhalothrin contributed from agricultural or urban runoff. Mitigation may be achieved by reducing the quantity of runoff and suspended solid content in runoff through wetlands, detention ponds, or vegetated ditches.